Characteristics, abundance and fertility of orphan eggs of the Lesser Rhea (Pterocnemia-Rhea ?pennata pennata): Implications for conservations

BARRI F.R.; MARTELLA M.B.; NAVARRO J.L.

JOURNAL OF ORNITHOLOGY

Springer

Año: 2008 vol. 149 p. 285 - 288

2193-7192

The Lesser Rhea (Pterocnemia-Rhea-pennatapennata) has a complex reproductive system that combinespolygyny with sequential polyandry, in which males buildthe nest, fully incubate the eggs and care for the young. Asoccurs with the Greater Rhea (Rhea americana), LesserRhea females sporadically lay eggs outside the nest(?orphan? eggs), which are not incubated and thus fail tohatch. We have examined the orphan eggs of Lesser Rheaover two separate breeding seasons to determine theirabundance and fertility status. During 2004 and 2005,weekly ground searches for orphan eggs were conducted ina wild population of Lesser Rhea in northwestern Patagonia,Argentina. During these searches the total number ofnests, eggs in each nest and orphan eggs laid outside thenests was recorded. Orphan eggs represented approximately7% of the total eggs laid in a breeding season. Sixfresh orphan eggs were artificially incubated, four of thembeing fertile. Orphan eggs seemed to have two origins:some were laid near deserted nests in the early to midreproductiveseason; others were probably laid by first-timebreeders and were found later in the reproductive season.Given the near-threatened status of the Lesser Rhea, harvestingand artificial incubation of orphan eggs, whichotherwise would be unproductive, may contribute significantlyto the conservation of this species, i.e., ?recovered?birds could be used for reintroduction or reinforcement ofwild Lesser Rhea populations.